This invention relates to small diameter optical waveguide fiber interconnect cables for indoor use containing single or dual tight buffered optical fibers.
Optical waveguide fibers are normally provided with a plastic protective coating applied by the fiber manufacturer directly over the cladding in order to protect the fiber. Such fibers are specified by an expression x/y, in which x is the outer diameter of the cladding and y is the outer diameter of the manufacturer applied coating or coatings.
In tight buffered cables, a protective tube is applied by the cable manufacturer directly to the outer surface of the fiber coating applied by the fiber manufacturer so that the fiber and the tube are in contact along substantially their length. In loose tube or composite buffer constructions, the coated optical fiber is separated from the protective tube.
Single and dual tight buffered optical waveguide fiber cables for the interconnection of equipment located indoors have been designed for voice, data, video, and imaging transmission in computer, process control, data entry, and wired office systems. These cables comprise a layer of loose aramid fiber tensile strength members disposed between either one or two tight buffered optical fibers and a surrounding outer plastic jacket. Such cables have been used as jumpers in distribution networks located within buildings. Such cables have also been available in plenum and riser rated versions. An example is Siecor Corporation's DIB.RTM. cable, which may be used for interface to FDDI and ESCON compatible connectors. Such cables have been available with single-mode, 50/125 .mu.m, 62.5/125 .mu.m, and 100/140 .mu.m multimode optical waveguide fibers. The cable outside diameter of a single fiber cable has typically been 2.9 mm, and the cable outside diameter of a dual fiber cable has been 4.8 mm.
Although the prior art cables have met industry needs, there are some applications in which space is at a premium. In large buildings, numerous fibers may be carried by a single duct or plenum and a multitude of jumpers may be connectorized in a single cross-connect cabinet. The cabinets are themselves designed to accommodate the size of the jumpers, and a reduction in the outer diameter of the jumpers would advantageously allow for a reduction in size of the cabinets. For these reasons, a further reduction in diameter of the cables would allow greater packing density of the fibers. However, such cables would still be expected to meet most of the specifications which are met by the cables that are currently available.
AT&T's minicord design provides a single fiber cable having an outer diameter of 1.60 mm. The cable meets a number of specifications listed in Bellcore publication GR-409.